A railroad (railway) system is basically designed to immediately stop a train when an earthquake has occurred. For example, JP-A-2012-183853 discloses a method that stops a train upon detection of an earthquake by stopping power supply, or causes a train that has received earthquake information transmitted from a ground device to apply a brake.
A known railroad system is normally designed to cause a train to apply an emergency brake when an earthquake has occurred in order to stop the train as early as possible. Specifically, the train may stop at an undesired position (section) (i.e., a position (section) at which a train should not be situated when an earthquake has occurred) (e.g., a position (section) on a bridge situated at a considerable height, a section situated near a slope of a mountain, and a section situated in the deepest area of a long tunnel).
The speed of a train may be reduced when an earthquake has occurred instead of stopping the train. In this case, however, since the speed of the train is reduced by applying an emergency brake or a maximum service brake, the above problem also occurs.